98ad82c784
Resolves: bz2175295 jiraProject == RHELPLAN-150659 Signed-off-by: John Kacur <jkacur@redhat.com>
152 lines
6.2 KiB
Diff
152 lines
6.2 KiB
Diff
From 5dc3750e747f93f9bb7987da3d47a8ab4a5a181e Mon Sep 17 00:00:00 2001
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From: Daniel Bristot de Oliveira <bristot@kernel.org>
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Date: Tue, 7 Feb 2023 22:48:51 +0100
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Subject: [PATCH] Documentation/rtla: Add hwnoise man page
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Add a man page for the new rtla hwnoise tool, mostly based in the
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rtla osnoise top.
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Link: https://lkml.kernel.org/r/27088e0f42a6129e9b75f789d78adff4171f2e79.1675805361.git.bristot@kernel.org
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Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
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Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
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Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
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Cc: Juri Lelli <juri.lelli@redhat.com>
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Cc: Clark Williams <williams@redhat.com>
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Cc: Jonathan Corbet <corbet@lwn.net>
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Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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---
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index.rst | 1 +
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rtla-hwnoise.rst | 107 +++++++++++++++++++++++++++++++++++++++++++++++
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2 files changed, 108 insertions(+)
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create mode 100644 Documentation/tools/rtla/rtla-hwnoise.rst
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diff --git a/Documentation/index.rst b/Documentation/index.rst
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index 840f0bf3e803..05d2652e4072 100644
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--- a/Documentation/index.rst
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+++ b/Documentation/index.rst
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@@ -17,6 +17,7 @@ behavior on specific hardware.
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rtla-timerlat
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rtla-timerlat-hist
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rtla-timerlat-top
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+ rtla-hwnoise
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.. only:: subproject and html
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diff --git a/Documentation/rtla-hwnoise.rst b/Documentation/rtla-hwnoise.rst
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new file mode 100644
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index 000000000000..fb1c52bbc00b
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--- /dev/null
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+++ b/Documentation/rtla-hwnoise.rst
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@@ -0,0 +1,107 @@
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+.. SPDX-License-Identifier: GPL-2.0
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+
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+============
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+rtla-hwnoise
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+============
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+------------------------------------------
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+Detect and quantify hardware-related noise
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+------------------------------------------
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+
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+:Manual section: 1
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+
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+SYNOPSIS
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+========
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+
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+**rtla hwnoise** [*OPTIONS*]
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+
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+DESCRIPTION
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+===========
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+
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+**rtla hwnoise** collects the periodic summary from the *osnoise* tracer
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+running with *interrupts disabled*. By disabling interrupts, and the scheduling
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+of threads as a consequence, only non-maskable interrupts and hardware-related
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+noise is allowed.
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+
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+The tool also allows the configurations of the *osnoise* tracer and the
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+collection of the tracer output.
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+
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+OPTIONS
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+=======
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+.. include:: common_osnoise_options.rst
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+
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+.. include:: common_top_options.rst
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+
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+.. include:: common_options.rst
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+
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+EXAMPLE
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+=======
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+In the example below, the **rtla hwnoise** tool is set to run on CPUs *1-7*
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+on a system with 8 cores/16 threads with hyper-threading enabled.
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+
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+The tool is set to detect any noise higher than *one microsecond*,
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+to run for *ten minutes*, displaying a summary of the report at the
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+end of the session::
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+
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+ # rtla hwnoise -c 1-7 -T 1 -d 10m -q
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+ Hardware-related Noise
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+ duration: 0 00:10:00 | time is in us
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+ CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
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+ 1 #599 599000000 138 99.99997 3 3 4 74
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+ 2 #599 599000000 85 99.99998 3 3 4 75
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+ 3 #599 599000000 86 99.99998 4 3 6 75
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+ 4 #599 599000000 81 99.99998 4 4 2 75
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+ 5 #599 599000000 85 99.99998 2 2 2 75
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+ 6 #599 599000000 76 99.99998 2 2 0 75
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+ 7 #599 599000000 77 99.99998 3 3 0 75
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+
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+
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+The first column shows the *CPU*, and the second column shows how many
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+*Periods* the tool ran during the session. The *Runtime* is the time
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+the tool effectively runs on the CPU. The *Noise* column is the sum of
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+all noise that the tool observed, and the *% CPU Aval* is the relation
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+between the *Runtime* and *Noise*.
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+
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+The *Max Noise* column is the maximum hardware noise the tool detected in a
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+single period, and the *Max Single* is the maximum single noise seen.
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+
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+The *HW* and *NMI* columns show the total number of *hardware* and *NMI* noise
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+occurrence observed by the tool.
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+
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+For example, *CPU 3* ran *599* periods of *1 second Runtime*. The CPU received
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+*86 us* of noise during the entire execution, leaving *99.99997 %* of CPU time
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+for the application. In the worst single period, the CPU caused *4 us* of
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+noise to the application, but it was certainly caused by more than one single
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+noise, as the *Max Single* noise was of *3 us*. The CPU has *HW noise,* at a
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+rate of *six occurrences*/*ten minutes*. The CPU also has *NMIs*, at a higher
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+frequency: around *seven per second*.
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+
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+The tool should report *0* hardware-related noise in the ideal situation.
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+For example, by disabling hyper-threading to remove the hardware noise,
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+and disabling the TSC watchdog to remove the NMI (it is possible to identify
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+this using tracing options of **rtla hwnoise**), it was possible to reach
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+the ideal situation in the same hardware::
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+
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+ # rtla hwnoise -c 1-7 -T 1 -d 10m -q
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+ Hardware-related Noise
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+ duration: 0 00:10:00 | time is in us
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+ CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
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+ 1 #599 599000000 0 100.00000 0 0 0 0
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+ 2 #599 599000000 0 100.00000 0 0 0 0
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+ 3 #599 599000000 0 100.00000 0 0 0 0
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+ 4 #599 599000000 0 100.00000 0 0 0 0
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+ 5 #599 599000000 0 100.00000 0 0 0 0
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+ 6 #599 599000000 0 100.00000 0 0 0 0
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+ 7 #599 599000000 0 100.00000 0 0 0 0
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+
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+SEE ALSO
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+========
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+
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+**rtla-osnoise**\(1)
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+
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+Osnoise tracer documentation: <https://www.kernel.org/doc/html/latest/trace/osnoise-tracer.html>
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+
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+AUTHOR
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+======
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+Written by Daniel Bristot de Oliveira <bristot@kernel.org>
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+
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+.. include:: common_appendix.rst
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--
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2.40.1
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